1. Field
Example embodiments relate to an operational amplifier, and more particularly, to a folded cascode operational amplifier having an improved phase margin through frequency compensation.
2. Description of the Related Art
Analog amplifiers include class A amplifiers, class B amplifiers, and class AB amplifiers. The class A amplifiers have high linearity but have low efficiency. As for the class B amplifier, energy loss is minimized but signal distortion occurs easily.
A folded cascode operational amplifier classified as a class AB amplifier which is a compromise between a class A amplifier and a class B amplifier has high efficiency because it is driven at a low voltage and has high linearity because an output voltage swings from a ground voltage to a power supply voltage, so that the folded cascode operational amplifier can be widely used in various kinds of electronic devices such as video devices and audio devices. However, the folded cascode operational amplifier is disadvantageous in that it is difficult to ensure a phase margin in an operating range.